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Benoît Véron - One of the best experts on this subject based on the ideXlab platform.
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Integrative Taxonomy of the Pavlovophyceae (Haptophyta): A Reassessment
Protist, 2011Co-Authors: El Mahdi Bendif, Ian Probert, Annie Hervé, Chantal Billard, Didier Goux, Christophe Lelong, Jean-paul Cadoret, Benoît VéronAbstract:The Pavlovophyceae (Haptophyta) contains four genera (Pavlova, Diacronema, Exanthemachrysis and Rebecca) and only thirteen characterised species, several of which are important in ecological and economic contexts. We have constructed molecular phylogenies inferred from sequencing of ribosomal gene markers with comprehensive coverage of the described diversity, using type strains when available, together with additional cultured strains. The morphology and ultrastructure of 12 of the described species was also re-examined and the pigment signatures of many culture strains were determined. The molecular analysis revealed that sequences of all described species differed, although those of Pavlova gyrans and P. pinguis were nearly identical, these potentially forming a single cryptic species complex. Four well-delineated genetic clades were identified, one of which included species of both Pavlova and Diacronema. Unique combinations of morphological/ultrastructural characters were identified for each of these clades. The ancestral pigment signature of the Pavlovophyceae consisted of a basic set of pigments plus MV chl cPAV, the latter being entirely absent in the Pavlova + Diacronema clade and supplemented by DV chl cPAV in part of the Exanthemachrysis clade. Based on this combination of characters, we propose a taxonomic revision of the class, with transfer of several Pavlova species to an emended Diacronema genus. The evolution of the class is discussed in the context of the phylogenetic reconstruction presented. (C) 2011 Elsevier GmbH. All rights reserved.
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Integrative Taxonomy of the Pavlovophyceae (Haptophyta): A Reassessment
Protist, 2011Co-Authors: El Mahdi Bendif, Ian Probert, Annie Hervé, Chantal Billard, Didier Goux, Christophe Lelong, Jean-paul Cadoret, Benoît VéronAbstract:The Pavlovophyceae (Haptophyta) contains four genera (Pavlova, Diacronema, Exanthemachrysis and Rebecca) and only thirteen characterised species, several of which are important in ecological and economic contexts. We have constructed molecular phylogenies inferred from sequencing of ribosomal gene markers with comprehensive coverage of the described diversity, using type strains when available, together with additional cultured strains. The morphology and ultrastructure of 12 of the described species was also re-examined and the pigment signatures of many culture strains were determined. The molecular analysis revealed that sequences of all described species differed, although those of Pavlova gyrans and P. pinguis were nearly identical, these potentially forming a single cryptic species complex. Four well-delineated genetic clades were identified, one of which included species of both Pavlova and Diacronema. Unique combinations of morphological/ultrastructural characters were identified for each of these clades. The ancestral pigment signature of the Pavlovophyceae consisted of a basic set of pigments plus MV chl cPAV, the latter being entirely absent in the Pavlova + Diacronema clade and supplemented by DV chl cPAV in part of the Exanthemachrysis clade. Based on this combination of characters, we propose a taxonomic revision of the class, with transfer of several Pavlova species to an emended Diacronema genus. The evolution of the class is discussed in the context of the phylogenetic reconstruction presented.
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nutritional value of six Pavlovophyceae for crassostrea gigas and pecten maximus larvae
Aquaculture, 2006Co-Authors: Ian Probert, Benoît Véron, E Ponis, J Le R Coz, Michel Mathieu, Rene RobertAbstract:Four unidentified new strains of Pavlovophyceae [Pavlova sp. AC 250 (Pfl), Pavlova sp. AC 248 (Psh), Pavlova sp. AC 251 (Pth), Pavlova sp. AC 538 (Psm)] and two known species [Pavlova pinguis (Ppi), Rebecca salina (ex Pavlova salina, Rsa)] were characterized (productivity, size, dry weight, ash, gross composition, fatty acids, sterols) and their nutritional value in bispecific diets were evaluated both on Crassostrea gigas and Pecten maximus larvae. All microalgae exhibited poor food value for C. gigas larvae. P. pinguis and R. salina did not sustain any growth, like the control starved larvae. No exo-toxicity of P. pinguis and R. salina was detected. These two species were weakly ingested by C. gigas larvae, while the four other pavlovophytes were effectively grazed. When used as food for P. maximus larvae, P. pinguis and Psh led to poor development. In contrast, a diet with Pfl resulted in significantly better growth than the control.
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PIGMENT SIGNATURES AND PHYLOGENETIC RELATIONSHIPS OF THE Pavlovophyceae (HAPTOPHYTA)1
Journal of Phycology, 2003Co-Authors: Kees Van Lenning, Mikel Latasa, Marta Estrada, Alberto G. Sáez, Linda K. Medlin, Ian Probert, Benoît Véron, Jeremy R. YoungAbstract:Variations in the HPLC-derived pigment composition of cultured Pavlovophyceae (Cavalier-Smith) Green et Medlin were compared with phylogenetic relationships inferred from 18S rDNA sequencing, morphological characteristics, and current taxonomy. The four genera described for this haptophyte class ( Diacronema Prauser emend. Green et Hibberd, Exanthemachrysis Lepailleur, Pavlova Butcher, and Rebecca Green) were represented by nine different species (one of which with data from GeneBank only). Chlorophylls a , c 1 , c 2 and MgDVP (Mg-[3,8-divinyl]-phytoporphyrin-13 2 methylcarboxylate) and the carotenoids fucoxanthin, diadinoxanthin, diatoxanthin, and � , � -carotene were detected in all cultures. Species only differed in the content of an unknown (diadinoxanthin-like) xanthophyll and two polar chl c forms, identified as a monovinyl (chl c 1 -like) and a divinyl (chl c 2 -like) compound. This is the first observation of the monovinyl form in haptophytes. Based on distribution of these two chl c forms, species were separated into Pavlovophyceae pigment types A, B, and C. These pigment types crossed taxonomic boundaries at the generic level but were in complete accordance with species groupings based on molecular phylogenetic relationships and certain ultrastructural characteristics (position and nature of pyrenoid, stigma, and flagella). These results suggest that characterization of the pigment signature of unidentified culture strains of Pavlovophyceae can be used to predict their phylogenetic affinities and vice versa. Additional studies have been initiated to evaluate this possibility for the haptophyte class Prymnesiophyceae.
Gérard Tremblin - One of the best experts on this subject based on the ideXlab platform.
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Light-dependent utilization of two radiolabelled carbon sources, sodium bicarbonate and sodium acetate, and relationships with long chain polyunsaturated fatty acid synthesis in the microalga Pavlova lutheri (Haptophyta)
European Journal of Phycology, 2011Co-Authors: Freddy Guihéneuf, Gérard Tremblin, Lionel Ulmann, Virginie MimouniAbstract:Pavlova lutheri is a common member of the Pavlovophyceae (Haptophyta), often used as a food source for aquatic filter-feeders and cultured in laboratories to produce high levels of polyunsaturated fatty acids (PUFAs), especially eicosapentaenoic and docosahexaenoic acids (EPA and DHA, respectively), which are known to have benefits for human health. Consequently, we investigated the pathways involved in the biosynthesis of long chain polyunsaturated fatty acids (LC-PUFAs) in this alga during photosynthesis in relation to light intensity. Using two radiolabelled carbon sources, [14C] sodium bicarbonate and [1-14C] sodium acetate, we obtained data suggesting that P. lutheri is able to synthesize LC-PUFAs by successive elongation and desaturation steps. It converts palmitic acid into palmitoleic acid by Δ7-desaturation. Moreover, significant incorporation of [1-14C] acetate (organic carbon) and its subsequent use in lipid metabolism suggest that P. lutheri may have a mixotrophic capacity for carbon assimilat...
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Effect of UV stress on the fatty acid and lipid class composition in two marine microalgae Pavlova lutheri (Pavlovophyceae) and Odontella aurita (Bacillariophyceae)
Journal of Applied Phycology, 2010Co-Authors: Freddy Guihéneuf, Virginie Mimouni, Lionel Ulmann, Manuela Fouqueray, Boris Jacquette, Gérard TremblinAbstract:Polyunsaturated fatty acids (PUFAs), especially eicosapentaenoic and docosahexaenoic acids (EPA and DHA), are abundantly synthesized by some phytoplankton species and play a key role in the marine food chain. However, they are generally considered to be sensitive to oxidation by UV radiation (UV-R). In order to investigate the effect of UV-R on the lipid composition of two marine microalgae, Pavlova lutheri and Odontella aurita, they were exposed to a combination of UVA-R and UVB-R with a total UV-R daily dose of 110 kJ m−2. Chlorophyll a, photochemical efficiency, and lipid composition were then determined on days 3, 5, and 8 of UV-R exposure. In P. lutheri, exposure to UV-R treatment led to a decrease in the proportions of PUFAs, such as EPA and DHA, especially into structural lipids (glycolipids and phospholipids). Our findings reveal a reduction of 20% in EPA levels and 16% in DHA levels, after 8 days of UV-R treatment. In O. aurita, exposure to UV-R did not change the fatty acid composition of the total lipids and lipid fractions of the cells. EPA levels remained high (27–28% of total lipids) during the 8 days of treatment. Consequently, the n-3 fatty acid content of P. lutheri was altered which highlights the sensitivity of this species to UV-R, whereas the results obtained for O. aurita suggest a more UV-R resistance. As a result, in latitude countries with medium UV-R level, outdoor “race-way” culture of O. aurita could yield a high-EPA algal biomass, whatever the seasonal variations in UV-R.
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Combined effects of irradiance level and carbon source on fatty acid and lipid class composition in the microalga Pavlova lutheri commonly used in mariculture
Journal of Experimental Marine Biology and Ecology, 2009Co-Authors: Freddy Guihéneuf, Virginie Mimouni, Lionel Ulmann, Gérard TremblinAbstract:Abstract Pavlova lutheri, a marine Pavlovophyceae, has been well documented as it is commonly used as a food source in mariculture. In this study, we investigated the combined effects of carbon sources and irradiance levels on the growth, lipid classes and fatty acid profiles of this microalga. The microalga was cultured at 15 °C with a 14 h photoperiod in artificial seawater containing bicarbonate or acetate as carbon source. The growth and lipid composition of P. lutheri were more sensitive to variations in light intensity than in carbon source. However, P. lutheri seems to be able to use acetate to growth cell and lipid metabolism. With the both carbon source, the lowest cellular lipid contents were obtained under low light intensity. The proportions of PUFAs, especially EPA, were significantly higher under low light, and saturating fatty acids and DHA levels were significantly higher under high light. In P. lutheri, galactolipids, a major component of chloroplast lipid membranes, made up approximately 54-66% of total lipids. The highest PUFA levels, such as those of EPA, were predominantly found in the galactolipid fraction when the cells were grown at low light, regardless of the carbon source. The consequent accumulation of n-3 fatty acids in the galactolipids could facilitate thylakoid membrane fluidity, and therefore the velocity of electron flow involved in photosynthesis during light acclimatization. These results could be used to optimize the culture conditions and the nutritional value of this microalga, which is used to feed marine invertebrates and fish larvae in mariculture hatcheries, and to produce n-3 fatty acids for human health care and nutrition.
Virginie Mimouni - One of the best experts on this subject based on the ideXlab platform.
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Light-dependent utilization of two radiolabelled carbon sources, sodium bicarbonate and sodium acetate, and relationships with long chain polyunsaturated fatty acid synthesis in the microalga Pavlova lutheri (Haptophyta)
European Journal of Phycology, 2011Co-Authors: Freddy Guihéneuf, Gérard Tremblin, Lionel Ulmann, Virginie MimouniAbstract:Pavlova lutheri is a common member of the Pavlovophyceae (Haptophyta), often used as a food source for aquatic filter-feeders and cultured in laboratories to produce high levels of polyunsaturated fatty acids (PUFAs), especially eicosapentaenoic and docosahexaenoic acids (EPA and DHA, respectively), which are known to have benefits for human health. Consequently, we investigated the pathways involved in the biosynthesis of long chain polyunsaturated fatty acids (LC-PUFAs) in this alga during photosynthesis in relation to light intensity. Using two radiolabelled carbon sources, [14C] sodium bicarbonate and [1-14C] sodium acetate, we obtained data suggesting that P. lutheri is able to synthesize LC-PUFAs by successive elongation and desaturation steps. It converts palmitic acid into palmitoleic acid by Δ7-desaturation. Moreover, significant incorporation of [1-14C] acetate (organic carbon) and its subsequent use in lipid metabolism suggest that P. lutheri may have a mixotrophic capacity for carbon assimilat...
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Effect of UV stress on the fatty acid and lipid class composition in two marine microalgae Pavlova lutheri (Pavlovophyceae) and Odontella aurita (Bacillariophyceae)
Journal of Applied Phycology, 2010Co-Authors: Freddy Guihéneuf, Virginie Mimouni, Lionel Ulmann, Manuela Fouqueray, Boris Jacquette, Gérard TremblinAbstract:Polyunsaturated fatty acids (PUFAs), especially eicosapentaenoic and docosahexaenoic acids (EPA and DHA), are abundantly synthesized by some phytoplankton species and play a key role in the marine food chain. However, they are generally considered to be sensitive to oxidation by UV radiation (UV-R). In order to investigate the effect of UV-R on the lipid composition of two marine microalgae, Pavlova lutheri and Odontella aurita, they were exposed to a combination of UVA-R and UVB-R with a total UV-R daily dose of 110 kJ m−2. Chlorophyll a, photochemical efficiency, and lipid composition were then determined on days 3, 5, and 8 of UV-R exposure. In P. lutheri, exposure to UV-R treatment led to a decrease in the proportions of PUFAs, such as EPA and DHA, especially into structural lipids (glycolipids and phospholipids). Our findings reveal a reduction of 20% in EPA levels and 16% in DHA levels, after 8 days of UV-R treatment. In O. aurita, exposure to UV-R did not change the fatty acid composition of the total lipids and lipid fractions of the cells. EPA levels remained high (27–28% of total lipids) during the 8 days of treatment. Consequently, the n-3 fatty acid content of P. lutheri was altered which highlights the sensitivity of this species to UV-R, whereas the results obtained for O. aurita suggest a more UV-R resistance. As a result, in latitude countries with medium UV-R level, outdoor “race-way” culture of O. aurita could yield a high-EPA algal biomass, whatever the seasonal variations in UV-R.
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Combined effects of irradiance level and carbon source on fatty acid and lipid class composition in the microalga Pavlova lutheri commonly used in mariculture
Journal of Experimental Marine Biology and Ecology, 2009Co-Authors: Freddy Guihéneuf, Virginie Mimouni, Lionel Ulmann, Gérard TremblinAbstract:Abstract Pavlova lutheri, a marine Pavlovophyceae, has been well documented as it is commonly used as a food source in mariculture. In this study, we investigated the combined effects of carbon sources and irradiance levels on the growth, lipid classes and fatty acid profiles of this microalga. The microalga was cultured at 15 °C with a 14 h photoperiod in artificial seawater containing bicarbonate or acetate as carbon source. The growth and lipid composition of P. lutheri were more sensitive to variations in light intensity than in carbon source. However, P. lutheri seems to be able to use acetate to growth cell and lipid metabolism. With the both carbon source, the lowest cellular lipid contents were obtained under low light intensity. The proportions of PUFAs, especially EPA, were significantly higher under low light, and saturating fatty acids and DHA levels were significantly higher under high light. In P. lutheri, galactolipids, a major component of chloroplast lipid membranes, made up approximately 54-66% of total lipids. The highest PUFA levels, such as those of EPA, were predominantly found in the galactolipid fraction when the cells were grown at low light, regardless of the carbon source. The consequent accumulation of n-3 fatty acids in the galactolipids could facilitate thylakoid membrane fluidity, and therefore the velocity of electron flow involved in photosynthesis during light acclimatization. These results could be used to optimize the culture conditions and the nutritional value of this microalga, which is used to feed marine invertebrates and fish larvae in mariculture hatcheries, and to produce n-3 fatty acids for human health care and nutrition.
Freddy Guihéneuf - One of the best experts on this subject based on the ideXlab platform.
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Light-dependent utilization of two radiolabelled carbon sources, sodium bicarbonate and sodium acetate, and relationships with long chain polyunsaturated fatty acid synthesis in the microalga Pavlova lutheri (Haptophyta)
European Journal of Phycology, 2011Co-Authors: Freddy Guihéneuf, Gérard Tremblin, Lionel Ulmann, Virginie MimouniAbstract:Pavlova lutheri is a common member of the Pavlovophyceae (Haptophyta), often used as a food source for aquatic filter-feeders and cultured in laboratories to produce high levels of polyunsaturated fatty acids (PUFAs), especially eicosapentaenoic and docosahexaenoic acids (EPA and DHA, respectively), which are known to have benefits for human health. Consequently, we investigated the pathways involved in the biosynthesis of long chain polyunsaturated fatty acids (LC-PUFAs) in this alga during photosynthesis in relation to light intensity. Using two radiolabelled carbon sources, [14C] sodium bicarbonate and [1-14C] sodium acetate, we obtained data suggesting that P. lutheri is able to synthesize LC-PUFAs by successive elongation and desaturation steps. It converts palmitic acid into palmitoleic acid by Δ7-desaturation. Moreover, significant incorporation of [1-14C] acetate (organic carbon) and its subsequent use in lipid metabolism suggest that P. lutheri may have a mixotrophic capacity for carbon assimilat...
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Effect of UV stress on the fatty acid and lipid class composition in two marine microalgae Pavlova lutheri (Pavlovophyceae) and Odontella aurita (Bacillariophyceae)
Journal of Applied Phycology, 2010Co-Authors: Freddy Guihéneuf, Virginie Mimouni, Lionel Ulmann, Manuela Fouqueray, Boris Jacquette, Gérard TremblinAbstract:Polyunsaturated fatty acids (PUFAs), especially eicosapentaenoic and docosahexaenoic acids (EPA and DHA), are abundantly synthesized by some phytoplankton species and play a key role in the marine food chain. However, they are generally considered to be sensitive to oxidation by UV radiation (UV-R). In order to investigate the effect of UV-R on the lipid composition of two marine microalgae, Pavlova lutheri and Odontella aurita, they were exposed to a combination of UVA-R and UVB-R with a total UV-R daily dose of 110 kJ m−2. Chlorophyll a, photochemical efficiency, and lipid composition were then determined on days 3, 5, and 8 of UV-R exposure. In P. lutheri, exposure to UV-R treatment led to a decrease in the proportions of PUFAs, such as EPA and DHA, especially into structural lipids (glycolipids and phospholipids). Our findings reveal a reduction of 20% in EPA levels and 16% in DHA levels, after 8 days of UV-R treatment. In O. aurita, exposure to UV-R did not change the fatty acid composition of the total lipids and lipid fractions of the cells. EPA levels remained high (27–28% of total lipids) during the 8 days of treatment. Consequently, the n-3 fatty acid content of P. lutheri was altered which highlights the sensitivity of this species to UV-R, whereas the results obtained for O. aurita suggest a more UV-R resistance. As a result, in latitude countries with medium UV-R level, outdoor “race-way” culture of O. aurita could yield a high-EPA algal biomass, whatever the seasonal variations in UV-R.
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Combined effects of irradiance level and carbon source on fatty acid and lipid class composition in the microalga Pavlova lutheri commonly used in mariculture
Journal of Experimental Marine Biology and Ecology, 2009Co-Authors: Freddy Guihéneuf, Virginie Mimouni, Lionel Ulmann, Gérard TremblinAbstract:Abstract Pavlova lutheri, a marine Pavlovophyceae, has been well documented as it is commonly used as a food source in mariculture. In this study, we investigated the combined effects of carbon sources and irradiance levels on the growth, lipid classes and fatty acid profiles of this microalga. The microalga was cultured at 15 °C with a 14 h photoperiod in artificial seawater containing bicarbonate or acetate as carbon source. The growth and lipid composition of P. lutheri were more sensitive to variations in light intensity than in carbon source. However, P. lutheri seems to be able to use acetate to growth cell and lipid metabolism. With the both carbon source, the lowest cellular lipid contents were obtained under low light intensity. The proportions of PUFAs, especially EPA, were significantly higher under low light, and saturating fatty acids and DHA levels were significantly higher under high light. In P. lutheri, galactolipids, a major component of chloroplast lipid membranes, made up approximately 54-66% of total lipids. The highest PUFA levels, such as those of EPA, were predominantly found in the galactolipid fraction when the cells were grown at low light, regardless of the carbon source. The consequent accumulation of n-3 fatty acids in the galactolipids could facilitate thylakoid membrane fluidity, and therefore the velocity of electron flow involved in photosynthesis during light acclimatization. These results could be used to optimize the culture conditions and the nutritional value of this microalga, which is used to feed marine invertebrates and fish larvae in mariculture hatcheries, and to produce n-3 fatty acids for human health care and nutrition.
Ian Probert - One of the best experts on this subject based on the ideXlab platform.
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Haptophyta
Handbook of the Protists, 2016Co-Authors: Wenche Eikrem, Linda K. Medlin, Ian Probert, Jorijntje Henderiks, Sebastian Rokitta, Björn Rost, Jahn Throndsen, Bente EdvardsenAbstract:Haptophyta are predominantly planktonic and phototrophic organisms that have their main distribution in marine environments worldwide. They are a major component of the microbial ecosystem, some form massive blooms and some are toxic. Haptophytes are significant players in the global carbonate cycle through photosynthesis and calcification. They are characterized by the haptonema, a third appendage used for attachment and food handling, two similar flagella, two golden-brown chloroplasts, and organic body scales that serve in species identification. Coccolithophores have calcified scales termed coccoliths. Phylogenetically Haptophyta form a well-defined group and are divided into two classes Pavlovophyceae and Coccolithophyceae (Prymnesiophyceae). Currently, about 330 species are described. Environmental DNA sequencing shows high haptophyte diversity in the marine pico- and nanoplankton, of which many likely represent novel species and lineages. Haptophyte diversity is believed to have peaked in the past and their presence is documented in the fossil record back to the Triassic, approximately 225 million years ago. Some biomolecules of haptophyte origin are extraordinarily resistant to decay and are thus used by geologists as sedimentary proxies of past climatic conditions
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Integrative Taxonomy of the Pavlovophyceae (Haptophyta): A Reassessment
Protist, 2011Co-Authors: El Mahdi Bendif, Ian Probert, Annie Hervé, Chantal Billard, Didier Goux, Christophe Lelong, Jean-paul Cadoret, Benoît VéronAbstract:The Pavlovophyceae (Haptophyta) contains four genera (Pavlova, Diacronema, Exanthemachrysis and Rebecca) and only thirteen characterised species, several of which are important in ecological and economic contexts. We have constructed molecular phylogenies inferred from sequencing of ribosomal gene markers with comprehensive coverage of the described diversity, using type strains when available, together with additional cultured strains. The morphology and ultrastructure of 12 of the described species was also re-examined and the pigment signatures of many culture strains were determined. The molecular analysis revealed that sequences of all described species differed, although those of Pavlova gyrans and P. pinguis were nearly identical, these potentially forming a single cryptic species complex. Four well-delineated genetic clades were identified, one of which included species of both Pavlova and Diacronema. Unique combinations of morphological/ultrastructural characters were identified for each of these clades. The ancestral pigment signature of the Pavlovophyceae consisted of a basic set of pigments plus MV chl cPAV, the latter being entirely absent in the Pavlova + Diacronema clade and supplemented by DV chl cPAV in part of the Exanthemachrysis clade. Based on this combination of characters, we propose a taxonomic revision of the class, with transfer of several Pavlova species to an emended Diacronema genus. The evolution of the class is discussed in the context of the phylogenetic reconstruction presented. (C) 2011 Elsevier GmbH. All rights reserved.
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Integrative Taxonomy of the Pavlovophyceae (Haptophyta): A Reassessment
Protist, 2011Co-Authors: El Mahdi Bendif, Ian Probert, Annie Hervé, Chantal Billard, Didier Goux, Christophe Lelong, Jean-paul Cadoret, Benoît VéronAbstract:The Pavlovophyceae (Haptophyta) contains four genera (Pavlova, Diacronema, Exanthemachrysis and Rebecca) and only thirteen characterised species, several of which are important in ecological and economic contexts. We have constructed molecular phylogenies inferred from sequencing of ribosomal gene markers with comprehensive coverage of the described diversity, using type strains when available, together with additional cultured strains. The morphology and ultrastructure of 12 of the described species was also re-examined and the pigment signatures of many culture strains were determined. The molecular analysis revealed that sequences of all described species differed, although those of Pavlova gyrans and P. pinguis were nearly identical, these potentially forming a single cryptic species complex. Four well-delineated genetic clades were identified, one of which included species of both Pavlova and Diacronema. Unique combinations of morphological/ultrastructural characters were identified for each of these clades. The ancestral pigment signature of the Pavlovophyceae consisted of a basic set of pigments plus MV chl cPAV, the latter being entirely absent in the Pavlova + Diacronema clade and supplemented by DV chl cPAV in part of the Exanthemachrysis clade. Based on this combination of characters, we propose a taxonomic revision of the class, with transfer of several Pavlova species to an emended Diacronema genus. The evolution of the class is discussed in the context of the phylogenetic reconstruction presented.
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nutritional value of six Pavlovophyceae for crassostrea gigas and pecten maximus larvae
Aquaculture, 2006Co-Authors: Ian Probert, Benoît Véron, E Ponis, J Le R Coz, Michel Mathieu, Rene RobertAbstract:Four unidentified new strains of Pavlovophyceae [Pavlova sp. AC 250 (Pfl), Pavlova sp. AC 248 (Psh), Pavlova sp. AC 251 (Pth), Pavlova sp. AC 538 (Psm)] and two known species [Pavlova pinguis (Ppi), Rebecca salina (ex Pavlova salina, Rsa)] were characterized (productivity, size, dry weight, ash, gross composition, fatty acids, sterols) and their nutritional value in bispecific diets were evaluated both on Crassostrea gigas and Pecten maximus larvae. All microalgae exhibited poor food value for C. gigas larvae. P. pinguis and R. salina did not sustain any growth, like the control starved larvae. No exo-toxicity of P. pinguis and R. salina was detected. These two species were weakly ingested by C. gigas larvae, while the four other pavlovophytes were effectively grazed. When used as food for P. maximus larvae, P. pinguis and Psh led to poor development. In contrast, a diet with Pfl resulted in significantly better growth than the control.
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A review of the phylogeny of the Haptophyta
Coccolithophores, 2004Co-Authors: Alberto G. Sáez, Ian Probert, Jeremy R. Young, Bente Edvardsen, Wenche Eikrem, Linda K. MedlinAbstract:Most haptophytes are unicellular, photosynthetic flagellates, although some have coccoid, colonial, amoeboid or filamentous stages. Nearly all have a characteristic filamentous appendage, the haptonema, arising between the two flagella. We have amassed small subunit rRNA gene sequences (18S rDNA) from 125 haptophytes and aligned the sequences with those of over 300 published and unpublished chlorophyll a+c algae. Phylogenies were constructed using Bayesian, minimum evolution and weighted maximum parsimony analyses. The high divergence (6%) between members of Pavlova and the remaining haptophytes supports the division of the Haptophyta into two classes: the Prymnesiophyceae and the Pavlovophyceae (Edvardsen et al. 2000). Four major clades within the Prymnesiophyceae were identified that correspond to known taxa: one clade embraces Phaeocystales; the second includes members of the Prymnesiales; the third represents the Isochrysidales; and the fourth the Coccolithales. Two other minor clades contain taxa whose sequences were derived from a gene clone library. In the absence of information on cell morphology associated with these sequences we are unable to determine whether they belong to existing orders or if new orders should be erected. These taxa are not strongly related to any of the known cultured taxa. One to two per cent divergence in the 18S rRNA gene analysis warrants a separation above the level of family.